This study investigated the growth performance, serum immunity, and cecal bacterial microbiota of broilers fed a diet in which soybean meal (SBM) was partially replaced with fermented soybean meal (FSBM) for 36 days. A total of 180 one-day-old male Cobb 500 broilers were randomly divided into three dietary groups (six replicates per group): corn-SBM diet (CC); 25% SBM replaced by FSBM (SC); 50% SBM replaced by FSBM (TC). The average daily gain (ADG) and feed conversion rates (FCR) were higher in SC than CC and TC groups (p < 0.05) during the growth (d 22–36) and whole (d 1–36) phases. No significant difference was observed in ADG and average daily feed intake (ADFI) between CC and TC groups during any phases. Dietary treatments increased serum IgA, IgG, and IgM, Chao 1, observed species, and the abundance of the phylum Fimicutes but decreased the proportion of Proteobacteria (p < 0.05). Dietary treatments increased the abundance of the genera Lachnospiraceae, Lachnoclostridium, Gastranaerophilales, and Lactobacillus but decreased the abundance of Escherichia-Shigella and Clostridiales (p < 0.05). Spearman’s correlations showed that the abundance of Gastranaerophilales was positively correlated with ADG and serum immunity, and the abundance of Lactobacillus was strongly positively with IgM. Thus, replacing 25% of SBM with FSBM improves the growth performance and serum immunity of broilers, possibly due to altered cecal microbial composition.

Rapeseed meal (RSM) is a common protein ingredient in animal diets, while the proportion of RSM in diets is limited because of its anti-nutritional factors. Fermentation based on mixed microbial strains appears to be a suitable approach to improve the nutritive value of rapeseed meal in animal feed. In this study, we evaluated the effects of fermentation on the apparent metabolizable energy (AME) values and standardized ileal digestibility (SID) of amino acids in RSM fed broilers. The AME and nitrogen-corrected apparent metabolizable energy (AMEn) values of RSM and fermented rapeseed meal (FRSM) were determined by the substitution method, with RSM and FRSM proportionally replacing the energy-yielding components of the basal diet by 30%. Results show that fermentation improved AME and AMEn of RSM from 7.44 to 8.51 MJ/kg and from 7.17 to 8.26 MJ/kg, respectively. In the second experiment, two experimental diets were formulated, with RSM and FRSM being the sole sources of amino acids. A nitrogen-free diet (NFD) was also formulated to determine endogenous amino acids losses (EAAL). Feeding on FRSM resulted in higher (p < 0.05) apparent ileal digestibility (AID) and SID of alanine, valine, isoleucine, leucine, tyrosine, lysine, arginine, and phenylalanine. No significant differences between RSM and FRSM were found for AID and SID of asparagine, histidine, threonine, serine, glutamine, praline, glycine, methionine, and cystine. FRSM had greater AMEn values and SID of amino acids compared to RSM, therefore, FRSM was nutritionally superior to RSM in broiler diets.

Bacillus subtilis has been widely used in animal husbandry as a potential alternative to antibiotics due to its excellent bacteriostasis and antioxidant activity. This study aims to investigate the effects of Bacillus subtilis on the protection of ducks from Escherichia coli infection and its mechanism. The four experimental groups include the negative control group, positive control group, antibiotic group and Bacillus subtilis group. Ducks in positive, antibiotic and Bacillus subtilis groups are orally administered with Escherichia coli and equivalent saline solution for the negative group. The results show that supplements with Bacillus subtilis enhances the performance and health status of the infected ducks. Moreover, Bacillus subtilis alleviates the increase in globulin, LPS and MDA, and the decrease in albumin, T-AOC and T-SOD in the serum caused by Escherichia coli infection. Bacillus subtilis also attenuates injury in the intestine and partially reverses the increase in ROS production and the depletion of ATP in the jejunum. These effects are accompanied with the change of related genes of the ribosome (13.54%) and oxidative phosphorylation (6.68%). Collectively, Bacillus subtilis alleviates the damage caused by Escherichia coli infection in ducks by activating ribosome and oxidative phosphorylation signaling to regulate antioxidant and energy metabolism.

The aims of this study were to screen and isolate a highly efficient strain from the rumen of a cow that can degrade the antigenic soy proteins in soybean meal (SBM) and improve the nutritional value of SBM by fermenting it with this strain. The safety of this strain was investigated with an acute oral toxicity test. A Bacillus amyloliquefaciens strain was successfully screened with plate tests and fermentation. After solid state fermentation of SBM with B. amyloliquefaciens for 24 h, the amounts of glycinin and β-conglycinin, two major antigenic proteins in SBM, decreased by 92.32% and 85.05%, respectively. The crude protein content in the fermented soybean meal (FSBM) increased by 17.54% compared with that in SBM. Notably, the trichloroacetic-acid-soluble protein (TCA-SP) content, particularly small peptides and free amino acids, was 9.97-fold higher in FSBM than in SBM. The in vitro dry matter digestibility and digestible energy of SBM increased from 62.91% to 72.52% and from 10.42 MJ/kg to 13.37 MJ/kg (dry matter basis), respectively, after fermentation. The acute oral toxicity test suggested that the strain exerted no harmful effects on the relative organ weights, the morphological tissue structure, or the health of mice. These results indicate that the B. amyloliquefaciens strain isolated in this study is a safe strain for animals, and could be used to improve the nutritional quality of SBM by solid-state fermentation.

Zanthoxylum bungeanum seed meal (ZBM), a novel plant protein raw material, has shown promising potential in enhancing the growth of broiler chickens as a substitute for soybean meal (SBM) in feed. In the artificial digestive experiment of vitro experiments, the digestibility of ZBM and SBM were assessed using the SDS-III Single Stomach Animal Biometric Digestion System. Subsequently, 180 1-day old AA chicks were divided into three groups for in vivo experiments: corn–soybean-meal-based diet (CON group); ZBM replacing 5% soybean meal in the basal diet (ZBM-1 group); ZBM replacing 10% soybean meal in the basal diet (ZBM-2 group). The experiment period lasted for 42 days. Compared to SBM, ZBM demonstrated higher crude protein content, dry matter digestibility, and extracorporeal digestible protein. Compared with the CON group, the broilers in the ZBM-2 group showed improved ADG and ADFI during the 1–21 d, 22–42 d, and 1–42 d periods (p < 0.05). Furthermore, the ZBM groups exhibited significant increases in slaughter performance compared with the CON group (p < 0.05). The substitution of ZBM for SBM also leads to a significant reduction in serum enzyme indicators (p < 0.05). Additionally, the lipoprotein and total cholesterol of the ZBM groups were significantly lower than those of the CON group (p < 0.05). Substituting SBM with ZBM significantly enhances the activity of superoxide dismutase and the content of immunoglobulin G in broiler serum, while reducing the content of malondildehyde (p < 0.05). The ZBM groups showed significantly higher utilization of dry matter, crude protein, and energy compared with the CON group (p < 0.05). In conclusion, the study confirmed that the substitution of SBM with 5–10% ZBM in broiler diets has a significant positive effect on growth, development, antioxidant capacity, immune function, and nutrient utilization. This study not only provides a theoretical foundation for the utilization of ZBM in broiler diets but also offers an effective approach for reducing reliance on soybean meal.

Two experiments were conducted to test the hypothesis that the apparent metabolizable energy (AME) and standardized ileal digestibility (SID) of amino acids (AA) in fermented soybean meal (FSBM) are greater than those in soybean meal (SBM). FSBM was produced by fermenting SBM with a mixture of Bacillus amyloliquefaciens, Lactobacillus acidophilus, and Saccharomyces cerevisiae. The fermentation process decreased trypsin inhibitor and crude fiber levels by 67.80% and 7.56%, while it increased the total amino acid content by 2.56%. In the first experiment, a substitution method was used to determine the AME and nitrogen-corrected AME (AMEn) of SBM and FSBM. A corn-SBM basal diet and two test diets consisting of 70% of the basal diet plus 30% SBM or FSBM were formulated. The results show that fermentation did not have an effect on the AME and AMEn concentrations of SBM (p > 0.05); the respective AME and AMEn values were 10.29 and 10.62 MJ/kg (DM basis) and 9.09 and 9.23 MJ/kg for SBM and FSBM. In the second experiment, a nitrogen-free diet was formulated to measure the endogenous AA flow, and the other two semi-purified diets containing SBM or FSBM as the sole source of AA were formulated. The results show that the AID and SID of isoleucine, leucine, phenylalanine, valine, cysteine, tyrosine, and aspartic acid were greater in FSBM than in SBM (p < 0.05). In conclusion, the fermentation of SBM by a mixture of B. amyloliquefaciens, L. acidophilus, and S. cerevisiae can improve its nutritional values and is a promising protein resource for broiler production.